Exemplary embodiments herein generally relate to vehicle frame assemblies. Across different vehicle models or types, it can be desirable to have many different vehicle lengths, or particular sections of such vehicles with many different lengths. For example, in a pickup truck, a cab area may include two full-sized doors, four full-sized doors, or two full-sized doors and two half-sized doors and a bed length of this type of vehicle can vary, e.g., from about 1.2 meters to about 2.4 meters. Accordingly, many possible combinations of cab length and bed length are possible. Of course, other types of vehicles can have variable lengths or sections with variable lengths, such as sport utility trucks, sport utility vehicles, minivans, crossovers, sedans, coupes, etc.
In conventional vehicle frames and constructions thereof, each such combination is a different vehicle model having a dedicated frame structure. Providing each vehicle model with its own dedicated frame structure, which conventionally is assembled from a collection of stamped parts, can be expensive and can make it difficult to efficiently manufacture several variable length vehicles on a single assembly line.
Some vehicle manufacturers employ a body-on-frame construction to provide some limited flexibility in varying vehicle designs. When body-on-frame construction techniques are employed, complete body assemblies (e.g., a cab structure or a bed structure) are mounted to a ladder frame. This allows the completed body assemblies to be modified and/or substituted without substantially changing the underlying ladder frame and/or other completed body assemblies mounted to the ladder frame. In the case of pickup trucks, for example, a cab assembly can be redesigned from one model year to the next without requiring substantial redesigning of the underlying ladder frame. In addition, a single ladder frame can support different types of cabs (regular, extended cab or full size) and/or different types of beds. In addition, ladder frames can be extended or lengthened by adding an auxiliary ladder frame to the main ladder frame. This could be used to support an extended bed or cab, or could be used to support an elongated vehicle (e.g., a livery vehicle). Drawbacks of body-on-frame designs include weight concerns causing lower performance and higher fuel consumption, compromised handling due to lack of torsion flexing and less ability to incorporate crumble zones for improved crash safety.